Question

What are the chromosome numbers in the following?
(I) Synergid cell in Gossypium
(II) Leaf cell in Allium
(III) Primary endosperm nucleus in Saccharum

• A. 48, 16, 36 respectively
• B. 52, 26, 32 respectively
• C. 26, 16, 120 respectively
• D. 48, 96, 24 respectively

Answer 1

Answer: (C)

26, 16, 120 respectively

Synergids are the part of female gametophyte/embryo sac that develops from meiosis in diploid megaspore mother cell i.e., gametogenesis and hence are haploid cells. Since the diploid chromosome number (2n) for Gossypium is 52; the synergids (n) will have 26 chromosomes. Leaf cells are the diploid cells which carry the same chromosome number as is found in other somatic cells of that species. Since the diploid chromosome number (2n) for Allium is 16; its leaf cells (2n) will have 16 chromosomes. Primary endosperm nucleus is the product of triple fusion wherein the haploid male gamete fuses with diploid secondary nucleus/central cell and forms triploid endosperm (3n). Since the haploid chromosome number for Saccharum is n=40; its primary endosperm nucleus (3n) will have 120 chromosomes.
This makes option C correct answer.